package com.dayuan.util;

import java.io.BufferedOutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Iterator;

import javax.servlet.http.HttpServletResponse;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRichTextString;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExportExcel<T> {
	 public void exportExcel(String[] headers,Collection<T> dataset, String fileName,HttpServletResponse response) {  
	        // 声明一个工作薄  
	        XSSFWorkbook workbook = new XSSFWorkbook();  
	        // 生成一个表格  
	        XSSFSheet sheet = workbook.createSheet(fileName);  
	        // 设置表格默认列宽度为15个字节  
	        sheet.setDefaultColumnWidth((short) 20);  
	        // 产生表格标题行  
	        XSSFRow row = sheet.createRow(0);  
	        for (short i = 0; i < headers.length; i++) {  
	            XSSFCell cell = row.createCell(i);  
	            XSSFRichTextString text = new XSSFRichTextString(headers[i]);  
	            cell.setCellValue(text);  
	        }  
	        try {  
	            // 遍历集合数据，产生数据行  
	            Iterator<T> it = dataset.iterator();  
	            int index = 0;  
	            while (it.hasNext()) {  
	                index++;  
	                row = sheet.createRow(index);  
	                T t = (T) it.next();  
	                // 利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值  
	                Field[] fields = t.getClass().getDeclaredFields();  
	                for (short i = 0; i < headers.length; i++) {  
	                    XSSFCell cell = row.createCell(i);  
	                    Field field = fields[i];  
	                    String fieldName = field.getName();  
	                    String getMethodName = "get" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);  
	                    Class tCls = t.getClass();  
	                    Method getMethod = tCls.getMethod(getMethodName, new Class[] {});  
	                    Object value = getMethod.invoke(t, new Object[] {});  
	                    // 判断值的类型后进行强制类型转换  
	                    String textValue = null;  
	                    // 其它数据类型都当作字符串简单处理  
	                    if(value != null && value != ""){  
	                        textValue = value.toString();  
	                    }  
	                    if (textValue != null) {  
	                        XSSFRichTextString richString = new XSSFRichTextString(textValue);  
	                        cell.setCellValue(richString);  
	                    }  
	                }  
	            }  
	            getExportedFile(workbook, fileName,response);  
	        } catch (Exception e) {  
	            e.printStackTrace();  
	        }   
	    }  
	      
	    /** 
	     *  
	     * 方法说明: 指定路径下生成EXCEL文件 
	     * @return 
	     */  
	    public void getExportedFile(XSSFWorkbook workbook, String name,HttpServletResponse response) throws Exception {  
	        BufferedOutputStream fos = null;  
	        try {  
	            String fileName = name + ".xlsx";  
	            response.setContentType("application/x-msdownload");  
	            response.setHeader("Content-Disposition", "attachment;filename=" + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));  
	            fos = new BufferedOutputStream(response.getOutputStream());  
	            //FileOutputStream out = new FileOutputStream("E://"+fileName);
	            workbook.write(fos);  
	        } catch (Exception e) {  
	            e.printStackTrace();  
	        } finally {  
	            if (fos != null) {  
	                fos.close();  
	            }  
	        }  
	    }  
}
